Primary Test: Magnification should be all that is required for the identification of this type of gemstone. The separation of colors, along with gas bubbles at the separation planes, will provide the needed evidence that you have a composite or doublet type of gemstone. Usually the top will be ruby or synthetic ruby with the remaining layers being glass. But any combination is possible.
Secondary Tests: In rare cases an immersion cell may be necessary to clearly view the plane separation.
Repair and Setting: Extreme caution with this material as any heating, including boiling, may cause the composite layers to separate. Customer should be informed of the composite nature of the stone before any repairs or resetting is initiated. No heat, no ultrasonic, and no cleaning solutions of any type.